THE POWER OF INCUMBENCY is a time-tested benefit in contested elections. Studies have shown over and over that officials seeking to hold onto their seats at all levels are successful more than 90 percent of the time, with name recognition and money flowing to incumbents at a rate that challengers rarely can overcome.

With all these advantages, you might think incumbents wouldn’t need any other edge. But in Massachusetts you would be wrong. State law puts one more arrow in the quiver of sitting officeholders, requiring that incumbents be listed first on the ballot. (Municipalities can override this requirement in local elections.) Massachusetts is the only state in the country with such a law.

“There’s an argument to be made that incumbents pass statutes that benefit incumbents,” says George Serra, a professor of political science at Bridgewater State University who studies electoral politics. “It is not uncommon. Many things happen in Massachusetts that don’t particularly surprise me.”

The law is not new. It was passed in 1948 after decades in which names were placed on the ballots in Massachusetts alphabetically regardless of whether there was a candidate for reelection or not. Other states list candidates differently, some alphabetically, some by random drawings, and some based on the number of votes a party’s candidates receive in previous elections for certain offices. Some leave it to the secretary of state to determine through his or her discretion. But nowhere is an incumbent given a mandated boost like here in Massachusetts.

The issue received some attention in the recent Fall River recall election when a judge ruled that Mayor Will Flanagan, the target of the recall, had a constitutional right to run in the recall election but he also ruled that state law required Flanagan to be listed first as the incumbent.  The decision was a blow to the recall organizers as well as the seven people on the ballot below him. Flanagan ultimately lost, but proponents of a change are not satisfied.

Senate Minority Leader Bruce Tarr of Gloucester, has offered a bill to allow random ballot placement every legislative session since 2005, but each time it has been sent to committee to die. Tarr plans to file the measure again this session.

“I think it ought to be a level playing field,” says Tarr. “I think it would be hard to argue it isn’t an unfair advantage to be first on the ballot.”

Indeed, numerous studies have shown there is a slight advantage to being the first name voters see in a race. A 2004 study in the Journal of Politics co-authored by two political science professors from Boston College and Yale University looked at the results of the 1998 Democratic primaries in New York City. The study analyzed voting in 79 districts, wards, and precincts where the names of the candidates were rotated and found that, in 71 of the contests, the person listed first had a greater share of votes than when they were listed elsewhere on the ballot in other districts.

“In seven of those 71 contests, the advantage to first position exceeded the winner’s margin of victory, suggesting that ballot position would have determined the election outcomes if one candidate had held the top spot in all precincts,” the authors wrote.

Serra, the Bridgewater State professor, says there is a “warm feeling” that goes with name recognition of incumbents despite the overall derision with which politics is viewed these days. Serra says the ability to deliver constituent services and the greater visibility that accompanies incumbency create a built-in advantage for candidates running for reelection. Putting their names at the top just makes it easier, he says.

Tarr says he hopes his colleagues will come around to seeing the error of their ways and back the change simply as a matter of decency and integrity.

“It has not affected me personally, but it is an issue that affects the integrity of the process generally,” he says. “I would hope that the compelling nature of creating a fair approach to ballot access will carry the day.”